首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2269篇
  免费   157篇
耳鼻咽喉   24篇
儿科学   46篇
妇产科学   72篇
基础医学   450篇
口腔科学   20篇
临床医学   202篇
内科学   393篇
皮肤病学   53篇
神经病学   323篇
特种医学   151篇
外科学   236篇
综合类   19篇
一般理论   1篇
预防医学   127篇
眼科学   5篇
药学   120篇
中国医学   3篇
肿瘤学   181篇
  2021年   30篇
  2020年   14篇
  2019年   41篇
  2018年   37篇
  2017年   29篇
  2016年   27篇
  2015年   38篇
  2014年   56篇
  2013年   67篇
  2012年   99篇
  2011年   88篇
  2010年   66篇
  2009年   50篇
  2008年   87篇
  2007年   110篇
  2006年   86篇
  2005年   93篇
  2004年   73篇
  2003年   100篇
  2002年   83篇
  2001年   86篇
  2000年   79篇
  1999年   57篇
  1998年   26篇
  1996年   19篇
  1995年   14篇
  1993年   19篇
  1992年   37篇
  1991年   50篇
  1990年   54篇
  1989年   44篇
  1988年   30篇
  1987年   35篇
  1986年   28篇
  1985年   45篇
  1984年   23篇
  1983年   26篇
  1982年   17篇
  1980年   14篇
  1979年   31篇
  1978年   23篇
  1977年   21篇
  1974年   15篇
  1973年   20篇
  1971年   22篇
  1967年   16篇
  1929年   20篇
  1928年   19篇
  1926年   34篇
  1925年   21篇
排序方式: 共有2426条查询结果,搜索用时 15 毫秒
1.
ObjectivesAlthough survival after a cancer diagnosis has improved considerably over the past 20 years, little is known about trends in health-related quality-of-life (HRQOL) for older prostate, breast, and lung cancer survivors.MethodsUsing a population-based registry with longitudinal patient reported outcomes (the National Cancer Institute Surveillance, Epidemiology and End Results database linked to Medicare Health Outcomes Survey), we analyzed Medicare Advantage patients diagnosed with cancer during 1998–2011, who completed surveys regarding HRQOL through 2013. ‘Early Era’ patients were treated during 1998–2003; ‘Late Era’ patients were treated during 2006–2011. After propensity score matching, post-diagnosis changes in health utility (HU), Physical Component Summary (PCS) and Mental Component Summary (MCS) scores were calculated and compared between the two eras.ResultWe identified 208 older patients with prostate, 276 with breast and 76 with lung cancer who were treated in the ‘Early Era’ and matched to equal numbers in the ‘Late Era’. Mean age of patients in early and late era was 72 and 73 years, respectively. The mean post-diagnosis decline in health utility for patients treated in the ‘Late Era’ was not significantly different from the ‘Early Era’ for any cancer (Prostate [early vs. late]: ?0.06 vs. -0.03, p = .09; Breast: ?0.03 vs. ?0.04, p = .65; Lung: ?0.07 vs. ?0.07, p = .95); nor for Physical Component Summary or Mental Component Summary scores.ConclusionOlder patients treated for prostate, breast or lung cancer in the later era reported similar outcomes of changes in HRQOL compared to earlier era patients.  相似文献   
2.
This study aims to identify the temporal kinetics of intravoxel incoherent motion (IVIM) MRI in patients with human papillomavirus‐associated (HPV+) oropharyngeal squamous cell carcinoma. Patients were enrolled under an Institutional Review Board (IRB)‐approved protocol as part of an ongoing prospective clinical trial. All patients underwent two MRI studies: a baseline scan before chemoradiotherapy and a mid‐treatment scan 3–4 weeks after treatment initiation. Parametric maps representing pure diffusion coefficient (D), pseudo‐diffusion coefficient (D*), perfusion fraction (f) and apparent diffusion coefficient (ADC) were generated. The Mann–Whitney U‐test was used to assess the temporal variation of IVIM metrics. Bayesian quadratic discriminant analysis (QDA) was used to evaluate the extent to which mid‐treatment changes in IVIM metrics could be combined to predict sites that would achieve complete response (CR) in multivariate analysis. Thirty‐one patients were included in the final analysis with 59 lesions. Pretreatment ADC and D values of the CR lesions (n = 19) were significantly lower than those of non‐CR lesions (n = 33). Mid‐treatment ADC, D and f values were significantly higher (p < 0.0001) than pretreatment values for all lesions. Each increase in normalized ΔADC of size 0.1 yielded a 1.45‐fold increase in the odds of CR (p < 0.0003), each increase in normalized ΔD of size 0.1 yielded a 1.53‐fold increase in the odds of CR (p < 0.0002), and each unit increase in Δf yielded a 2.29‐fold increase in the odds of CR (p < 0.02). Combined ΔD and ΔADC were integrated into a multivariate prediction model and attained an AUC of 0.87 (95% confidence interval: 0.79, 0.96), as well as a sensitivity of 0.63, specificity of 0.85 and accuracy of 0.78, under leave‐one‐out cross‐validation. In conclusion, IVIM is feasible and potentially useful in the prediction and assessment of the early response of HPV+ oropharyngeal squamous cell carcinoma to chemoradiotherapy. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
3.
4.
In recent years, there has been a growing recognition of a dissociative subtype of posttraumatic stress disorder (D-PTSD), characterized by experiences of depersonalization (DP) and derealization (DR), among individuals with PTSD. Little is known, however, about how experiences of DP and/or DR are associated with the experience of other PTSD symptoms. The central aim of the present paper was to explore the associations among DP, DR, and other PTSD symptoms by means of a network analysis of cross-sectional data for 557 participants whose overall self-reported PTSD symptom severity warranted a probable PTSD diagnosis. Three notable findings emerged: (a) a strong association between DP and DR, (b) the identification of DP as the most central symptom in the network, and (c) the discovery that clusters of symptoms in the network were roughly consistent with DSM-5 PTSD criteria. We discuss these findings in light of some considerations, including the nature of our sample and the limits of interpreting cross-sectional network models.  相似文献   
5.
The efficacy and safety of a novel once-daily extended-release ciprofloxacin (ciprofloxacin ER) 500-mg dose were compared with those of an immediate-release ciprofloxacin (ciprofloxacin IR) 250-mg twice-daily dose, each administered orally for 3 days in the treatment of acute uncomplicated urinary tract infection (uUTI) in women. Adult female outpatients (mean age, 39 years) with clinical signs and symptoms of acute uUTI and a positive pretreatment urine culture (> or =10(5) CFU/ml) were enrolled in a multicenter, randomized, double-blind, noninferiority trial. Patients were assessed at a test-of-cure visit (4 to 11 days posttreatment) and a late-posttreatment visit (4 to 6 weeks posttreatment) for microbiological and clinical outcomes and safety. The primary efficacy endpoint and microbiological eradication rate at the test-of-cure visit in the ciprofloxacin ER group (254/272; 93.4%) were noninferior to those in the ciprofloxacin IR group (225/251; 89.6%) (95% confidence interval [CI] of difference, -0.99%, 8.59%). Clinical-cure rates at the test-of-cure visit were 85.7% (233/272) for ciprofloxacin ER and 86.1% (216/251) for ciprofloxacin IR (95% CI of difference, -6.37%, 5.57%). At the late-posttreatment visit, microbiological and clinical outcomes were similar for the two treatments and consistent with test-of-cure results. Both treatments were well tolerated, but the frequencies of nausea and diarrhea were lower in the ciprofloxacin ER group than in the ciprofloxacin IR group (nausea, ER, 0.6%; IR, 2.2%; P = 0.033; diarrhea, ER, 0.2%; IR, 1.4%; P = 0.037). Once-daily ciprofloxacin ER was safe, effective, and noninferior to twice-daily ciprofloxacin IR in the treatment of acute uUTI. Additionally, ciprofloxacin ER was associated with significantly reduced frequencies of nausea and diarrhea.  相似文献   
6.
BACKGROUND: Hemoglobin A(1c) (HbA(1c)) has been used in controlled trials for the last 10 years but has never been evaluated in clinical practice as an effective parameter for clinical outcome. We investigated the trend for glycemic control over 11 years in one county of 350,000 citizens. METHODS: We studied 226,382 HbA(1c-DCCT-aligned) from 39,455 patients in whom routine monitoring for diabetes was initiated in 1993, 1996, or 2001. The trend in glycemic control was investigated in groups by probit plots, and in individual patients by target plots. RESULTS: From 1993 to 2001, the number of HbA(1c) measurements increased three-fold. The number of new monitoring series increased from 0.22% to 0.27% of the county population, and the number of patients monitored using HbA(1c) as a proxy for diabetes increased from 0.5% to 1.5%. A proportional reduction in high HbA(1c) concentrations of 5% was identified in the 1993 group, compared to 15% in the 1996 group, and 20% in the 2001 group. The percentage of patients with diabetic first HbA(1c) experiencing normalization increased from 8% to 30% for males and from 9% to 24% for females (1993-2001). The percentage of HbA(1c) concentrations that were not normalized decreased from 78% to 53% for males and from 83% to 59% for females (1993-2001). The median HbA(1c) at initiation of monitoring decreased from 8.7% in 1993 to 7.5% in 2001 (p < 10(-5)). The number of normal first HbA(1c) results in monitoring series increased from 7% to 17% for males and from 8% to 22% for females. Up to 10% of subjects developed diabetic concentrations during monitoring. CONCLUSION: On average, patients with diabetic first HbA(1c) concentrations (> or =6.62%) showed an improvement in glycemic control from 5% in 1993 to 20% in 2001. High concentrations were easiest to reduce. In patients with originally diabetic HbA(1c) levels, 66% on average showed improved glycemic control in the 2001 series compared to 50% in the 1993 series. An average of 6% (1993) vs. 9% (2001) with originally normal HbA(1c) levels showed an upward trend inHbA(1c) levels. Median HbA(1c) at initiation of monitoring decreased from 8.7% in 1993 to 7.5% in 2001 (p < 10(-5)). The incidence of new cases was constant.  相似文献   
7.
The purpose of this study was to examine the sensitivity and peak force prediction capability of the interpolated twitch technique (ITT) performed during submaximal and maximal voluntary contractions (MVCs) in subjects with the ability to maximally activate their plantar flexors. Twelve subjects performed two MVCs and nine submaximal contractions with the ITT method to calculate percent voluntary inactivation (%VI). Additionally, two MVCs were performed without the ITT. Polynomial models (linear, quadratic and cubic) were applied to the 10-90% VI and 40-90% VI versus force relationships to predict force. Peak force from the ITT MVC was 6.7% less than peak force from the MVC without the ITT. Fifty-eight percent of the 10-90% VI versus force relationships were best fit with nonlinear models; however, all 40-90% VI versus force relationships were best fit with linear models. Regardless of the polynomial model or the contraction intensities used to predict force, all models underestimated the actual force from 22% to 28%. There was low sensitivity of the ITT method at high contraction intensities and the predicted force from polynomial models significantly underestimated the actual force. Caution is warranted when interpreting the % VI at high contraction intensities and predicted peak force from submaximal contractions.  相似文献   
8.
We presented a novel experimental aneurysm model for studies in left ventricular (LV) reconstruction techniques and assessed LV function. In eight pigs, the LV radius and geometry were enlarged surgically on the beating heart by inserting an aortic allograft construct. Haemodynamics and LV dimensions were assessed by echocardiography at baseline and under dobutamine stress. Surgery was successfully performed without lethal blood loss or arrhythmias. LV end-diastolic and end-systolic short-axis areas increased from 13.0 ± 1.7 to 17.0 ± 4.3 cm(2) (P = 0.001) and from 4.0 ± 0.9 to 13.0 ± 2.6 cm(2) (P = 0.001), respectively. Stroke volume decreased from 56 ± 11 to 33 ± 16 ml (P = 0.001). Incremental dobutamine infusion concurred with a biphasic response on fractional area shortening. Mitral valve insufficiency ranging from grades 2 to 4 was observed. In the pig, a novel, reproducible aneurysm model for acute cardiac dysfunction was created on the beating heart. Innovative (surgical) strategies for (staged) reconfiguration of the ventricle, e.g. adjustable Dor procedures and stepwise volume restraining cardiac support devices, can be tested for efficacy using this acute model.  相似文献   
9.
OBJECTIVE: The purpose of this study was to determine the efficacy and safety of a novel extended-release metformin in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: Adults with type 2 diabetes (newly diagnosed, treated with diet and exercise only, or previously treated with oral diabetic medications) were randomly assigned to receive one of three extended-release metformin treatment regimens (1,500 mg/day q.d., 1,500 mg/day twice daily, or 2,000 mg/day q.d.) or immediate-release metformin (1,500 mg/day twice daily) in a double-blind 24-week trial. RESULTS: Significant decreases (P < 0.001) in mean HbA(1c) (A1C) levels were observed by week 12 in all treatment groups. The mean changes from baseline to end point in the two groups given 1,500 mg extended-release metformin (-0.73 and -0.74%) were not significantly different from the change in the immediate-release metformin group (-0.70%), whereas the 2,000-mg extended-release metformin group showed a greater decrease in A1C levels (-1.06%; mean difference [2,000 mg extended-release metformin - immediate-release metformin]: -0.36 [98.4% CI -0.65 to -0.06]). Rapid decreases in fasting plasma glucose levels were observed by week 1, which continued until week 8, and were maintained for the duration of the study. The overall incidence of adverse events was similar for all treatment groups, but fewer patients in the extended-release metformin groups discontinued treatment due to nausea during the initial dosing period than in the immediate-release metformin group. CONCLUSIONS: Once- or twice-daily extended-release metformin was as safe and effective as twice-daily immediate-release metformin and provided continued glycemic control for up to 24 weeks of treatment.  相似文献   
10.
Nurses' Attitudes and Practice Related to Hospice Care   总被引:1,自引:0,他引:1  
Purpose: To describe characteristics, attitudes, and communications of nurses regarding hospice and caring for terminally ill patients.
Design: A cross-sectional study of randomly selected nurses (n=180) from six randomly selected Connecticut community hospitals was conducted in 1998 and 1999.
Methods: Hospice-related training, knowledge and attitudes, demographic and practice characteristics, and personal experience with hospice were assessed with a self-administered questionnaire (response rate=82%). Logistic regression was used to model the effects of hospice-related training, knowledge, and attitudes on these outcomes, adjusting for personal experience and other characteristics of nurses.
Findings: Characteristics associated with discussion of hospice with both patients and families included greater religiousness, having a close family member or friend who had used hospice, and reporting satisfaction with hospice caregivers. Greater self-rated knowledge was significantly associated with discussion of hospice with patients. Attitudinal scores indicating greater comfort with initiating discussion and greater perceived added benefit of hospice were significantly associated with discussion with patients' families.
Conclusions: Nurses' discussion of hospice with terminally ill patients and their families are related to the potentially modifiable factors of self-rated knowledge and attitudes revealing comfort with discussion and perceived benefit of hospice care.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号